Biodegradation method of sulfonylurea herbicide

Abstract

The invention discloses a biodegradation method of sulfonylurea herbicides, and relates to the technical field of herbicide residue degradation. The biodegradation method of the sulfonylurea herbicide comprises the following specific steps that soil in which the sulfonylurea herbicide is used for a long time is turned over, and a prepared nutrition improver is spread to the turned surface of the soil, the method comprises the following steps of: spraying a degrading bacterium agent on sown soil by using magnesium chloride, potassium humate, soybean root powder, peanut root powder, spanishneedles herb, photosynthetic bacteria, rice ash and drinking water, circularly turning the soil for multiple times, and covering the soil with a film for 30 days. According to the method, soil is primarily improved through the nutrition improver, the pH value of the soil is balanced, meanwhile, reproduction of microorganisms in the soil is facilitated, certain resistance is provided for subsequent bacterial strains to degrade residues of sulfonylurea herbicides, pure degradation bacterial strains are screened out through culture, purification and separation of the degradation bacterial strains, and the degradation rate is further increased.

Description

Technical Field

[0001] The invention relates to the technical field of herbicide residue degradation, in particular to a biodegradation method for sulfonylurea herbicides. Background Art

[0002] Sulfonylurea herbicides are currently the largest class of herbicides in the world. Since G. Levitt of DuPont first reported that this type of compound has herbicidal activity and developed the wheat field herbicide chlorsulfuron for the first time in 1982, which brought weed control into the era of super high efficiency, it has developed into a large category of herbicides. This type of herbicide has special effects on many annual or perennial weeds and is widely used to control weeds in rice fields, soybean fields, corn fields, wheat crop fields, rapeseed fields, lawns and other non-arable land. So far, dozens of varieties have been commercialized.

[0003] Currently, companies participating in the registration of such varieties include BASF, Bayer CropScience, DuPont, ISK, Monsanto, Nissan Chemical, Takeda, Syngenta, etc. The sulfonylurea herbicides currently widely used in my country mainly include benzylsulfuron-methyl, ethametsulfuron-methyl, chlorsulfuron-methyl, pyrazosulfuron-methyl, bensulfuron-methyl, thiasulfuron-methyl, nicosulfuron-methyl, chlorimuron-methyl, etc. With the continuous expansion of pesticide varieties, problems with the use of herbicides have also emerged. Some varieties, such as chlorsulfuron-methyl, chlorsulfuron-methyl, ethametsulfuron-methyl, etc., can cause pesticide damage to subsequent sensitive crops with a small amount of residue in the soil; on the other hand, due to the lack of understanding of the characteristics of this herbicide by many business users and farmers, many residue problems have occurred, and different degrees of pesticide damage will be caused to crops such as melons, rapeseed, sugar beets, potatoes, sorghum, etc. planted in the second year, causing huge economic losses to farmers. Therefore, the safety of subsequent crops caused by the residues of this type of herbicide in the soil has aroused widespread concern. Therefore, it is of great theoretical and practical significance to study how to solve the problem of herbicide residue toxicity and the pollution caused to Polygonatum sibiricum.

[0004] For example, the biodegradation method of sulfonylurea herbicides disclosed in Chinese patent publication number CN109758713A can effectively degrade the sulfonylurea herbicides remaining in the soil where sulfonylurea herbicides have been applied for a long time, and the degradation rate can reach about 85%. The operation method is simple and environmentally friendly. In step (1), by spraying nutrient solution into the soil, the activity of the degrading bacteria in the soil can be effectively improved, thereby improving the degradation effect of the sulfonylurea herbicides; after the synergistic effect of Brevibacterium epidermidis and Achromobacterium, the degradation effect of the sulfonylurea herbicides on each other is promoted, and the degradation rate of the sulfonylurea herbicides in the soil can reach about 85%, thereby avoiding the harm of the sulfonylurea herbicides to crops.

[0005] First, the above-mentioned degradation method uses degradation bacteria to complete the degradation effect of sulfonylurea herbicides, but the purification, separation and screening of the degradation bacteria are not carried out, resulting in the degradation bacteria not being pure degradation strains, affecting their degradation rate. Therefore, the degradation rate can be further improved. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a method for biodegrading sulfonylurea herbicides, which solves the problems raised in the above-mentioned background technology.

[0007] To achieve the above object, the present invention is implemented by the following technical scheme: a biodegradation method of sulfonylurea herbicides, comprising the following specific steps: S1: turning over the soil that has been treated with sulfonylurea herbicides for a long time, and spreading the prepared nutrient improver on the surface of the turned soil, wherein the nutrient improver is made of the following components in parts by weight: 3-8 parts of magnesium chloride, 2-4 parts of potassium humate, 1-4 parts of soybean root powder, 3-8 parts of peanut root powder, 4-7 parts of Bidens pilosa, 2-4 parts of photosynthetic bacteria, 11-13 parts of rice ash, and 100-150 parts of drinking water; S2: Spray the degradation bacteria on the soil where the seeds have been sown. After several cycles of tilling the soil, cover the soil with film for 30 days. After the degradation is completed, spray the nutrient improver and degradation bacteria again.

[0008] A further improvement of the technical solution of the present invention is that the spraying amount of the nutrient improver in S1 is 400 mL / m 2 The spraying amount of the nutrient improver in S2 is 200mL / m 2 .

[0009] A further improvement of the technical solution of the present invention is that the initial spraying amount of the degradation bacterial agent in S2 is 600 mL / m 2 The secondary spraying amount of the degradation agent in S2 is 100 mL / m 2 .

[0010] A further improvement of the technical solution of the present invention is that the preparation of the degradation bacterial agent comprises the following specific steps: T1: Take a soil sample that has been exposed to sulfonylurea herbicides for a long time and dissolve it in sterile saline to prepare the required soil suspension; T2: Add the prepared enrichment medium into the flask, inoculate 10% of the inoculum into the soil suspension, and culture in a shaking incubator at 28°C and 150 rpm for 5 days; T3: The obtained culture solution was inoculated into a fresh enrichment medium at a ratio of 10%, and then cultured in a shaking incubator at 28°C and 150 r / min for 5 days. After 10 cycles of inoculation, the concentration of chlorimuron-methyl reached 1000 mg / L, and the degradation strain culture was obtained; T4: After the strains are enriched in T3, the strain culture suspension is diluted step by step, and 0.15-0.2 mL of the sample solution is spread on beef extract peptone medium, Martin's medium and Gao's medium No. 1 plates respectively, and cultured at 28°C for 2 days. A single colony is picked and cultured on a separation plate, and the colony morphology and bacterial state are combined for separation and purification to obtain a pure degradation strain. The pure degradation strain is inoculated in beef extract peptone medium for preservation and prepared into a bacterial agent when used.

[0011] A further improvement of the technical solution of the present invention is that the beef extract peptone culture medium is composed of 0.3 g beef extract, 0.5 g peptone, 0.5 g sodium chloride, 2 g agar, and 100 mL distilled water; The Martensitic culture medium consists of 0.5 g peptone, 1 g glucose, 0.1 g potassium dihydrogen phosphate, 0.05 g magnesium sulfate, 2 g agar, 100 mL distilled water, and 0.33 mL 1% Bengal red aqueous solution.

[0012] A further improvement of the technical solution of the present invention is that the enrichment culture medium consists of 0.5 g of peptone, 0.1 g of potassium dihydrogen phosphate, 0.05 g of magnesium sulfate, and 100 mL of distilled water.

[0013] A further improvement of the technical solution of the present invention is that the coating particle size in S1 is controlled within a range of 0.35 mm to 0.45 mm.

[0014] A further improvement of the technical solution of the present invention is that the concentration of chlorimuron-ethyl in the enrichment culture medium used in T2 is 100 mg / L.

[0015] Compared with the prior art, the beneficial effect of the present invention is that the preliminary improvement of the soil is completed by the nutrient modifier, the pH value of the soil is balanced and it is beneficial to the reproduction of microorganisms in the soil, and a certain resistance is provided for the subsequent bacterial strain to degrade the residues of the sulfonylurea herbicide, and the pure degradation strain is screened out by culturing and purifying the degradation strain, thereby further improving the degradation rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The degradation flow chart of the biodegradation method of sulfonylurea herbicides; Figure 2 The figure is a schematic diagram of the process for preparing degradation strains in the biodegradation method of sulfonylurea herbicides. DETAILED DESCRIPTION

[0017] Various exemplary embodiments, features and aspects of the present application will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0018] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0019] In addition, in order to better illustrate the present application, numerous specific details are provided in the specific embodiments below. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In some examples, methods, means, and elements well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present application.

[0020] The present invention provides a method for biodegrading sulfonylurea herbicides, comprising the following specific steps: S1: turning over the soil that has been treated with sulfonylurea herbicides for a long time, and spreading the prepared nutrient improver on the surface of the turned soil, wherein the nutrient improver is made of the following components in parts by weight: 3-8 parts of magnesium chloride, 2-4 parts of potassium humate, 1-4 parts of soybean root powder, 3-8 parts of peanut root powder, 4-7 parts of Bidens pilosa, 2-4 parts of photosynthetic bacteria, 11-13 parts of rice ash, and 100-150 parts of drinking water; S2: Spray the degradation bacteria on the soil where the seeds have been sown. After several cycles of tilling the soil, cover the soil with film for 30 days. After the degradation is completed, spray the nutrient improver and degradation bacteria again.

[0021] The spraying amount of the nutrient improver in S1 is 400mL / m 2 The spraying amount of the nutrient improver in S2 is 200mL / m 2 .

[0022] The initial spraying amount of the degradation agent in S2 is 600 mL / m 2 The secondary spraying amount of the degradation agent in S2 is 100 mL / m 2 .

[0023] The preparation of the degradation bacterial agent comprises the following specific steps: T1: Take a soil sample that has been exposed to sulfonylurea herbicides for a long time and dissolve it in sterile saline to prepare the required soil suspension; T2: Add the prepared enrichment medium into the flask, inoculate 10% of the inoculum into the soil suspension, and culture in a shaking incubator at 28°C and 150 rpm for 5 days; T3: The obtained culture solution was inoculated into a fresh enrichment medium at a ratio of 10%, and then cultured in a shaking incubator at 28°C and 150 r / min for 5 days. After 10 cycles of inoculation, the concentration of chlorimuron-methyl reached 1000 mg / L, and the degradation strain culture was obtained; T4: After the strains were enriched in T3, the strain culture suspension was diluted step by step, and 0.15-0.2 mL of the sample solution was spread on beef extract peptone medium, Martin's medium and Gao's medium No. 1 plates respectively, and cultured at 28°C for 2 days. A single colony was picked and cultured on a separation plate, and the colony morphology and bacterial state were combined for separation and purification to obtain a pure degradation strain. The pure degradation strain was inoculated in beef extract peptone medium for preservation and prepared into a bacterial agent when used.

[0024] The beef extract peptone medium consists of 0.3 g beef extract, 0.5 g peptone, 0.5 g sodium chloride, 2 g agar, and 100 mL distilled water; The Martensitic culture medium consists of 0.5 g peptone, 1 g glucose, 0.1 g potassium dihydrogen phosphate, 0.05 g magnesium sulfate, 2 g agar, 100 mL distilled water, and 0.33 mL 1% Bengal red aqueous solution.

[0025] The enrichment medium consisted of 0.5 g of peptone, 0.1 g of potassium dihydrogen phosphate, 0.05 g of magnesium sulfate, and 100 mL of distilled water.

[0026] The coating particle size in S1 is controlled within the range of 0.35 mm to 0.45 mm.

[0027] The concentration of chlorimuron-ethyl in the enrichment medium used in T2 is 100 mg / L.

[0028] Embodiment 1: 10% chlorimuron-methyl, 20% chlorimuron-methyl, 30% chlorimuron-methyl and 40% chlorimuron-methyl were evenly sprayed on 4 kinds of test soils with a small spray pot, stirred evenly, and the original concentration of chlorimuron-methyl in the soil was 0.5mg / kg, and the relative soil moisture content was adjusted to 25%, and the flower pot was filled with a plastic film to maintain the soil moisture content, and a small hole was punctured on the film with a needle to allow ventilation. The soil was watered 5 days apart to keep the soil moisture basically unchanged.

[0029] The four groups of test soils were respectively set up with corresponding degradation tests, divided into experimental group one, experimental group two, experimental group three, and experimental group four.

[0030] The maize taproot length inhibition rate method was used to determine the concentration of chlorimuron-methyl in the soil in each experimental group.

[0031] Experimental group 1: S1: The soil containing 10% chlorimuron-methyl was turned over, and the prepared nutrient improver was spread on the surface of the turned soil, wherein the nutrient improver was made of the following components in parts by weight: 3 parts of magnesium chloride, 2 parts of potassium humate, 1 part of soybean root powder, 3 parts of peanut root powder, 4 parts of Bidens pilosa, 2 parts of photosynthetic bacteria, 11 parts of rice ash and 100 parts of drinking water; S2: Spray the degradation bacteria on the soil where the seeds have been sown. After several cycles of tilling the soil, cover the soil with film for 30 days. After the degradation is completed, spray the nutrient improver and degradation bacteria again.

[0032] The spraying amount of the nutrient improver in S1 is 400 mL / m 2 The spraying amount of the nutrient improver in S2 is 200mL / m 2 The initial spraying amount of the degradation agent in S2 is 600 mL / m 2 The secondary spraying amount of the degradation agent in S2 is 100 mL / m 2 .

[0033] The preparation of the degradation bacterial agent comprises the following specific steps: T1: Take a soil sample that has been exposed to sulfonylurea herbicides for a long time and dissolve it in sterile saline to prepare the required soil suspension; T2: Add the prepared enrichment medium into the flask, inoculate 10% of the inoculum into the soil suspension, and culture in a shaking incubator at 28°C and 150 rpm for 5 days; T3: The obtained culture solution was inoculated into a fresh enrichment medium at a ratio of 10%, and then cultured in a shaking incubator at 28°C and 150 r / min for 5 days. After 10 cycles of inoculation, the concentration of chlorimuron-methyl reached 1000 mg / L, and the degradation strain culture was obtained; T4: After the strains were enriched in T3, the strain culture suspension was diluted step by step, and 0.15-0.2 mL of the sample solution was spread on beef extract peptone medium, Martin's medium and Gao's medium No. 1 plates respectively, and cultured at 28°C for 2 days. A single colony was picked and cultured on a separation plate, and the colony morphology and bacterial state were combined for separation and purification to obtain a pure degradation strain. The pure degradation strain was inoculated in beef extract peptone medium for preservation and prepared into a bacterial agent when used.

[0034] Experimental Group 2: S1: turning over the soil containing 20% ​​chlorimuron-methyl, and spreading the prepared nutrient improver on the surface of the turned soil, wherein the nutrient improver is made of the following components in parts by weight: 4 parts of magnesium chloride, 3 parts of potassium humate, 2 parts of soybean root powder, 4 parts of peanut root powder, 5 parts of Bidens pilosa, 3 parts of photosynthetic bacteria, 12 parts of rice ash and 110 parts of drinking water; S2: Spray the degradation bacteria on the soil where the seeds have been sown. After several cycles of tilling the soil, cover the soil with film for 30 days. After the degradation is completed, spray the nutrient improver and degradation bacteria again.

[0035] The spraying amount of the nutrient improver in S1 is 400 mL / m 2The spraying amount of the nutrient improver in S2 is 200mL / m 2 The initial spraying amount of the degradation agent in S2 is 600 mL / m 2 The secondary spraying amount of the degradation agent in S2 is 100 mL / m 2 .

[0036] The preparation of the degradation bacterial agent comprises the following specific steps: T1: Take a soil sample that has been exposed to sulfonylurea herbicides for a long time and dissolve it in sterile saline to prepare the required soil suspension; T2: Add the prepared enrichment medium into the flask, inoculate 10% of the inoculum into the soil suspension, and culture in a shaking incubator at 28°C and 150 rpm for 5 days; T3: The obtained culture solution was inoculated into a fresh enrichment medium at a ratio of 10%, and then cultured in a shaking incubator at 28°C and 150 r / min for 5 days. After 10 cycles of inoculation, the concentration of chlorimuron-methyl reached 1000 mg / L, and the degradation strain culture was obtained; T4: After the strains were enriched in T3, the strain culture suspension was diluted step by step, and 0.15-0.2 mL of the sample solution was spread on beef extract peptone medium, Martin's medium and Gao's medium No. 1 plates respectively, and cultured at 28°C for 2 days. A single colony was picked and cultured on a separation plate, and the colony morphology and bacterial state were combined for separation and purification to obtain a pure degradation strain. The pure degradation strain was inoculated in beef extract peptone medium for preservation and prepared into a bacterial agent when used.

[0037] Experimental group three: S1: turning over the soil containing 30% chlorimuron-methyl, and spreading the prepared nutrient improver on the surface of the turned soil, wherein the nutrient improver is made of the following components in parts by weight: 5 parts of magnesium chloride, 4 parts of potassium humate, 3 parts of soybean root powder, 5 parts of peanut root powder, 6 parts of Bidens pilosa, 4 parts of photosynthetic bacteria, 13 parts of rice ash and 120 parts of drinking water; S2: Spray the degradation bacteria on the soil where the seeds have been sown. After several cycles of tilling the soil, cover the soil with film for 30 days. After the degradation is completed, spray the nutrient improver and degradation bacteria again.

[0038] The spraying amount of the nutrient improver in S1 is 400 mL / m 2 The spraying amount of the nutrient improver in S2 is 200mL / m 2 The initial spraying amount of the degradation agent in S2 is 600 mL / m 2 The secondary spraying amount of the degradation agent in S2 is 100 mL / m 2 .

[0039] The preparation of the degradation bacterial agent comprises the following specific steps: T1: Take a soil sample that has been exposed to sulfonylurea herbicides for a long time and dissolve it in sterile saline to prepare the required soil suspension; T2: Add the prepared enrichment medium into the flask, inoculate 10% of the inoculum into the soil suspension, and culture in a shaking incubator at 28°C and 150 rpm for 5 days; T3: The obtained culture solution was inoculated into a fresh enrichment medium at a ratio of 10%, and then cultured in a shaking incubator at 28°C and 150 r / min for 5 days. After 10 cycles of inoculation, the concentration of chlorimuron-methyl reached 1000 mg / L, and the degradation strain culture was obtained; T4: After the strains were enriched in T3, the strain culture suspension was diluted step by step, and 0.15-0.2 mL of the sample solution was spread on beef extract peptone medium, Martin's medium and Gao's medium No. 1 plates respectively, and cultured at 28°C for 2 days. A single colony was picked and cultured on a separation plate, and the colony morphology and bacterial state were combined for separation and purification to obtain a pure degradation strain. The pure degradation strain was inoculated in beef extract peptone medium for preservation and prepared into a bacterial agent when used.

[0040] Experimental Group 4: S1: turning over the soil containing 40% chlorimuron-methyl, and spreading the prepared nutrient improver on the surface of the turned soil, wherein the nutrient improver is made of the following components in parts by weight: 5 parts of magnesium chloride, 4 parts of potassium humate, 3 parts of soybean root powder, 5 parts of peanut root powder, 6 parts of Bidens pilosa, 4 parts of photosynthetic bacteria, 13 parts of rice ash and 130 parts of drinking water; S2: Spray the degradation bacteria on the soil where the seeds have been sown. After several cycles of tilling the soil, cover the soil with film for 30 days. After the degradation is completed, spray the nutrient improver and degradation bacteria again.

[0041] The spraying amount of the nutrient improver in S1 is 400 mL / m 2 The spraying amount of the nutrient improver in S2 is 200mL / m 2 The initial spraying amount of the degradation agent in S2 is 600 mL / m 2 The secondary spraying amount of the degradation agent in S2 is 100 mL / m 2 .

[0042] The preparation of the degradation bacterial agent comprises the following specific steps: T1: Take a soil sample that has been exposed to sulfonylurea herbicides for a long time and dissolve it in sterile saline to prepare the required soil suspension; T2: Add the prepared enrichment medium into the flask, inoculate 10% of the inoculum into the soil suspension, and culture in a shaking incubator at 28°C and 150 rpm for 5 days; T3: The obtained culture solution was inoculated into a fresh enrichment medium at a ratio of 10%, and then cultured in a shaking incubator at 28°C and 150 r / min for 5 days. After 10 cycles of inoculation, the concentration of chlorimuron-methyl reached 1000 mg / L, and the degradation strain culture was obtained; T4: After the strains were enriched in T3, the strain culture suspension was diluted step by step, and 0.15-0.2 mL of the sample solution was spread on beef extract peptone medium, Martin's medium and Gao's medium No. 1 plates respectively, and cultured at 28°C for 2 days. A single colony was picked and cultured on a separation plate, and the colony morphology and bacterial state were combined for separation and purification to obtain a pure degradation strain. The pure degradation strain was inoculated in beef extract peptone medium for preservation and prepared into a bacterial agent when used.

[0043] Example 2: The specific measurement steps of test groups 1, 2, 3, and 4 are as follows: 20.0 g of soil sample were accurately weighed, placed in a ground-mouth conical flask, 60 mL of methanol / 0.01% phosphoric acid aqueous solution was added, and the extract was extracted on a gyroscopic oscillator for 1 h, and then the extract was transferred to a 50-m centrifuge tube, centrifuged at 4000 r / min for 5 min, filtered with filter paper, 30 ml of the supernatant was taken, rotary evaporated at 45 ° C, fixed to volume with 2 m methanol, and detected by a high performance liquid chromatograph-ultraviolet detector after passing through a 0.22 um filter membrane; Among them, the concentration of chlorimuron-methyl in experimental group one was measured to be 1.24%, the growth inhibition rate of corn taproot was 26.25%, and the final degradation rate of chlorimuron-methyl was 91.9%; the concentration of chlorimuron-methyl in experimental group two was measured to be 3.58%, the growth inhibition rate of corn taproot was 27.84%, and the final degradation rate of chlorimuron-methyl was 93.7%; the concentration of chlorimuron-methyl in experimental group three was measured to be 5.87%, the growth inhibition rate of corn taproot was 24.25%, and the final degradation rate of chlorimuron-methyl was 90.1%; the concentration of chlorimuron-methyl in experimental group four was measured to be 8.41%, the growth inhibition rate of corn taproot was 27.4%, and the final degradation rate of chlorimuron-methyl was 93.1%.

[0044] This shows that the degradation rate of the degradation strain obtained through enrichment, separation and purification is as high as over 90% for sulfonylurea herbicides.

[0045] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0046] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for biodegradation of sulfonylurea herbicides, characterized in that: The specific steps include: S1: turning over the soil that has been treated with sulfonylurea herbicides for a long time, and spreading the prepared nutrient improver on the surface of the turned soil, wherein the nutrient improver is made of the following components in parts by weight: 3-8 parts of magnesium chloride, 2-4 parts of potassium humate, 1-4 parts of soybean root powder, 3-8 parts of peanut root powder, 4-7 parts of Bidens pilosa, 2-4 parts of photosynthetic bacteria, 11-13 parts of rice ash, and 100-150 parts of drinking water; S2: Spray the degradation bacteria on the soil where the seeds have been sown. After several cycles of tilling the soil, cover the soil with film for 30 days. After the degradation is completed, spray the nutrient improver and degradation bacteria again.

2. The method for biodegradation of sulfonylurea herbicides according to claim 1, characterized in that: The spraying amount of the nutrient improver in S1 is 400mL / m 2 The spraying amount of the nutrient improver in S2 is 200mL / m 2 .

3. The biodegradation method of a sulfonylurea herbicide according to claim 1, characterized in that: The initial spraying amount of the degradation agent in S2 is 600 mL / m 2 The secondary spraying amount of the degradation agent in S2 is 100 mL / m 2 .

4. The method for biodegradation of sulfonylurea herbicides according to claim 1, characterized in that: The preparation of the degradation bacterial agent comprises the following specific steps: T1: Take a soil sample that has been exposed to sulfonylurea herbicides for a long time and dissolve it in sterile saline to prepare the required soil suspension; T2: Add the prepared enrichment medium into the flask, inoculate 10% of the inoculum into the soil suspension, and culture in a shaking incubator at 28°C and 150 rpm for 5 days; T3: The obtained culture solution was inoculated into a fresh enrichment medium at a ratio of 10%, and then cultured in a shaking incubator at 28°C and 150 r / min for 5 days. After 10 cycles of inoculation, the concentration of chlorimuron-methyl reached 1000 mg / L, and the degradation strain culture was obtained; T4: After the strains were enriched in T3, the strain culture suspension was diluted step by step, and 0.15-0.2 mL of the sample solution was spread on beef extract peptone medium, Martin's medium and Gao's medium No. 1 plates respectively, and cultured at 28°C for 2 days. A single colony was picked and cultured on a separation plate, and the colony morphology and bacterial state were combined for separation and purification to obtain a pure degradation strain. The pure degradation strain was inoculated in beef extract peptone medium for preservation and prepared into a bacterial agent when used.

5. The method for biodegradation of sulfonylurea herbicides according to claim 4, characterized in that: The beef extract peptone medium consists of 0.3 g beef extract, 0.5 g peptone, 0.5 g sodium chloride, 2 g agar, and 100 mL distilled water; The Martensitic culture medium consists of 0.5 g peptone, 1 g glucose, 0.1 g potassium dihydrogen phosphate, 0.05 g magnesium sulfate, 2 g agar, 100 mL distilled water, and 0.33 mL 1% Bengal red aqueous solution.

6. The method for biodegradation of sulfonylurea herbicides according to claim 4, characterized in that: The enrichment medium consisted of 0.5 g of peptone, 0.1 g of potassium dihydrogen phosphate, 0.05 g of magnesium sulfate, and 100 mL of distilled water.

7. The method for biodegradation of sulfonylurea herbicides according to claim 1, characterized in that: The coating particle size in S1 is controlled within the range of 0.35 mm to 0.45 mm.

8. The method for biodegradation of sulfonylurea herbicides according to claim 4, characterized in that: The concentration of chlorimuron-ethyl in the enrichment medium used in T2 is 100 mg / L.

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